This invention relates to braking systems in the field of hydrostatic motion-transmissions. There are many examples of safety-brakes which render immovable the shaft of a fluid motor as soon as the pressure of feed to the motor drops below a predetermined level. Such brakes are used with devices for driving a winch or a vehicle wheel by an hydraulic motor.
Release of the brake is effected by a fluid control coupled to the control of the fluid feed to the main motor. It is known that one important problem is the production of a sequence device which enables the control to be automated. On this point known devices are generally complicated and do not provide satisfactory operation.